Single-Point Load Cell Selection: Platform Size, Mounting and Signal

Single-point load cell selection depends on the platform that the sensor is expected to support. The term describes a sensor used beneath a complete platform, with off-centre performance subject to specified conditions. It does not mean that any tray can be bolted onto a sensor with sufficient nominal capacity. Deck size, tare, mounting and load placement have to be checked together.

Single-point load cell selection needs an approved platform envelope

The METRAVON MV-LC0211 lists capacities of 50, 100, 150, 200, 250, 300 and 500 kg. The reference drawing shows the sensor body and its attachment dimensions, including a 150 mm overall length. That length is not the maximum allowed tray length.

The published reference data do not state a maximum platform size to use as an automatic approval. Submit the proposed deck length and width, its stiffness and the possible load positions for confirmation with the selected capacity. Do not copy an allowed platform size from a visually similar sensor or infer it from the bolt spacing.

This matters when a customer wants to enlarge a bench-scale tray or add a side extension. The same total mass can produce a different moment and position error after the load moves farther from the intended geometry. An unchanged capacity label does not validate the modified platform.

Use the MV-LC0211 data for the decisions they actually support

The published sensitivity tolerance is +/-0.2 mV/V; it is not a specification for weighing error. Likewise, the IP67 reference does not establish chemical resistance or permission to use any cleaning method. Confirm the actual material option, cable termination and environment for the offered unit.

At an illustrative 5 V excitation, nominal full-scale signal change is 10 mV. On a 100 kg version, a 1 kg increment would correspond to 0.1 mV under ideal proportional response. These calculations help assess the input signal; they do not guarantee resolution, accuracy or noise performance. Test the smallest required increment with the complete electronics and mechanics.

Fit the deck without clamping out the measurement

Use the drawing to distinguish the fixed attachment from the platform attachment and confirm the permitted loading direction. The mounting faces should fit without twisting the body into place. Fasteners, engagement and tightening requirements belong to the approved assembly details, not a guessed torque based only on the thread size.

Keep clear of fixed guards and overload stops during normal weighing. A platform that touches a stop can give a plausible centre reading while producing different errors elsewhere. Keep cables, hoses and conveyor connections from creating another force path into the deck.

Design for maintenance as well as assembly. The cable should remain protected and accessible without pulling on the sensor, and the cell should be removable using a safe support arrangement. Changes to its mounting or cable configuration require an assessment of the installed calibration.

Check positions, not only span

After assembly, test with appropriate reference loads at the centre and agreed off-centre positions. Record zero before and after loading, repeat selected positions and compare loading with unloading. Use the actual deck and fixtures, not a temporary plate that avoids the most demanding positions.

A single sensing channel does not have the same corner-balancing procedure as four separate cells. If position errors remain, investigate the platform dimensions, stiffness, mounting and unwanted contacts before attempting to compensate electronically. The corner-error article explains how repeated position tests help distinguish these effects.

For a moving conveyor or rapid filling station, also test the reading at the required decision time. A product reference to checkweighing does not specify the speed, settling time or dynamic accuracy of the customer's machine. Those requirements need separate confirmation.

What to send before requesting the sensor

Send METRAVON a dimensioned platform drawing, deck and fixture weight, minimum and maximum product load, possible placement area, required increment and reading time. Include cleaning conditions and the intended instrument. Use the enquiry page to request confirmation of the platform envelope and the exact supplied configuration.

If the platform or loading conditions fall outside the confirmed single-point arrangement, review a distributed-support design instead of enlarging the tray by assumption. The platform architecture guide compares those options.

Questions about adapting an existing bench scale

Q1. Can taring a heavy tray recover the full product capacity?

No. Tare changes the displayed zero, not the force carried by the sensor. The tray and permanent fixtures still consume physical capacity. Assess gross load and expected peaks before deciding the available product range.

Q2. Can a higher-capacity version use the same calibration settings?

Do not assume that. Even if the nominal mV/V sensitivity is shared, the relationship between load and signal changes with capacity, and the supplied sensitivity can vary. Check the drawing, configure the actual version and calibrate the installed scale before accepting its readings.

Summary

Confirm the platform envelope before ordering the single-point sensor. Use its electrical data to select the readout, then verify the completed deck at its real load positions. Capacity and a matching bolt pattern are useful checks, but neither replaces approval of the platform arrangement.